MONDAY, March 15 (HealthDay News) -- Scientists have believed that testosterone and estrogen play a major role in regulating blood pressure, but a new study in mice suggests that female sex chromosomes could also be key, at least after menopause begins.

In the study, researchers genetically engineered male mice to have female chromosomes (XX) and females to have male chromosomes (YY). They found that the chromosomes affected the rodents' blood pressure on their own.

"XX mice have a greater magnitude of hypertension than XY mice regardless of whether they are male or female," lead investigator Kathryn Sandberg, director of the Georgetown University Medical Center for the Study of Sex Differences in Health, Aging and Disease, said in a news release from Georgetown.

"Up until now, it has been impossible to separate the influence of sex chromosomes from the effects of sex hormones, and in this paper, we have shown for the first time that sex chromosomes are impacting blood pressure -- independent of sex hormones," she said. "That is not to say sex hormones don't matter in blood pressure regulation, because they do, but we now know they aren't the only players."

Why does this matter?

Because "there is a real jump in blood pressure and incidence of hypertension in menopausal women, and while the condition is treatable, blood pressure in many of these women is not fully under control, making them far more susceptible to cardiovascular and kidney disease and stroke," Sandberg said. "Therefore, it would be wonderful to have specific therapies that target the root cause of this hypertension."